1. Field of the Invention
The present invention relates to a contactor for a semiconductor device, and more particularly, to a contactor for a semiconductor device having a two-point-contact type socket used for an evaluation test, a mass production test, or a burn-in test of flat package type ICs and to a contact method.
A multitude of the flat package type ICs are used for portable devices such as mobile phones, digital video cameras, digital still cameras and notebook type personal computers. Especially, narrow pitch flat package type or CSP (Chip Size Package) type power ICs, power control ICs, or flat package type ICs other than the power IC such as system LSIs have functional pins through which great current flows. In a semiconductor test, when providing a current to the functional pins, voltage drop occurs in a target supply voltage in a case where contact resistance of the contact pins is high. Accordingly, the target supply voltage is not obtained, and as a result, it is impossible to provide sufficient current to the functional pins. Thus, when performing the evaluation test, mass production test, or burn-in test of the flat package type IC, a two-point-contact type socket that helps a small current to pass through by reducing the contact resistance so as to achieve a high-precision and stable test is used.
2. Description of the Related Art
FIG. 1 shows an IC socket used for a test of conventional flat package type ICs. The IC socket has a one point type structure in which respective contactors 3 are provided for each of leads of IC 1. The contactors 3 contact undersurfaces of the leads of the flat package type IC 1. The contactors 3 are fixed to a socket body 4 in line so as to correspond to an arrangement of the leads of the IC 1. A package table 2 is arranged inside the arrangement of the contactors 3. The package table 2 is supported by a spring and can move up and down.
When the IC 1 is placed on the package table 2, each of the leads of the IC 1 is positioned directly above a contact end of the respective contactor 3. When a pressure portion 4 is moved downward, heads of a pressure portion 5 press the leads of the IC 1. The package table 2 moves downward and the leads of the IC 1 contact the contact ends of the contactors 3. By further moving the pressure portion 5 downward, the contactors 3 are elastically deformed. Stability of the contactors 3 corresponds to contact pressure between the contactors 3 and the leads of the IC 1.
The IC socket shown in FIG. 1 is called a one-point-contact type socket since each of the contactors 3 contacts a respective one of the leads of the IC 1 at one point. With regard to the one-point-contact type socket, it is conceivable that sufficient electrical contact is not obtained when foreign matter exists at the contact points or when influenced by vibration or the like. In order to prevent such cases, the two-point-contact type socket is used. The two-point-contact type socket reduces occurrence of imperfect contact due to the foreign matter, vibrations and the like by providing two contact points for each of the leads of the IC.
In the two-point-contact type socket, by insulating two contactors for a single IC lead from each other, it is possible to use one contactor for sensing (for detecting a resistance value and a current value) and to use the other contactor for forcing (for supplying voltage and current). Accordingly, it is possible to measure the current actually provided to the IC leads during the test, and to accurately control predetermined supply voltage and current that are to be provided to the IC leads.
In Japanese Laid-Open Utility Model Application No. 5-28049, a two-point-contact type socket is disclosed. The so disclosed two-point-contact type socket has a structure in which two contactors (a first contactor and second contactor) are arranged in line separately under an IC lead. The first contactor contacts an undersurface of the IC lead. A third contactor, which is provided at a cover of the socket, contacts an upper surface of the IC lead that is on the first contactor and contacts the second contactor at the same time.
Additionally, Japanese Laid-Open Patent Application No. 2000-195630 discloses another two-point-contact type socket. In the so disclosed two-point-contact type socket, two contactors are provided in a socket body and arranged in line under an IC lead. The two contactors sandwich an insulating sheet there between, or one of the two contactors has a surface on which an insulating film is formed so that the two contactors contact each other via the insulating film.
Further, Japanese Laid-Open Patent Application No. 11-297442 discloses another two-point-contact type socket. In the so disclosed two-point-contact type socket, two contactors are provided for each single IC lead. One contactor contacts an undersurface of the IC lead, and the other contactor contacts an upper surface of the IC lead by an operation of a pressure portion. A contact socket of this structure is a so-called open top type socket in which the contactor moves back upward by pressing the pressure portion and the contactor holds down the IC lead when the pressure portion is not pressed.
Compact and narrow pitch flat package type or CSP type power ICs are used in mobile devices and notebook type personal computers. In order to accurately and stably perform tests of these types of ICs, inexpensive sockets are required that can easily and positively realize two point contact, can maintain stability over a long period of time, and can be easily replaced. Further, in factories dealing with different kinds of packages, sockets are required that can be applied to mass production tests without special mechanism change of IC handlers.
However, in order to achieve two-point contact, it is necessary to make two independent contactors contact a single IC lead. With regard to this requirement, in the socket disclosed in Japanese Laid-Open Patent Application No. 05-028049, it is not easy to accurately and simultaneously make the first contactor contact the second contactor using the third contactor provided at the cover of the socket after setting the IC on the IC holding board. In addition, there is a disadvantage in that moving the IC handler toward the socket and conducting contact operations must be performed separately.
Further, in the socket disclosed in Japanese Laid-Open Patent Application No. 11-297442, the contactors separate from the leads when the pressure portion is pressed down, and the contactors contact the upper surfaces of the leads when the pressure portion is not pressed down. Accordingly, the contact operation is performed by pressing down the pressure portion before mounting the IC on the package table and terminating the press-down operation after the mounting of the IC is completed so as to let the pressure portion return to the original position. Thus, there is no flexibility of setting contact pressure since the contact pressure is a constant value set by the structure of the contactors. Furthermore, an operation of taking out the IC from the socket must be performed in a state where the pressure portion is pressed down again. For this reason, it is necessary to perform the operation of pressing down the pressure portion both when the IC handler mounts the IC to the socket and when the IC handler takes the IC out of the socket. Thus, a socket is required that enables mounting and removing of the IC to be performed easily.
A general object of the present invention is to provide an improved and useful semiconductor device contactor and contact method that enable placing and taking out of the IC to be performed by the same operation as that of a conventional one point contact socket, and can achieve positive two point contact.
In order to achieve the above-mentioned object, there is provided according to one aspect of the present invention, a contactor for a semiconductor device, comprising: a placing table on which a semiconductor device is placed; lower side contactors contacting terminals of the semiconductor device from a lower side when the semiconductor device is placed on the placing table; upper side contactors having heads that are movable up and down with respect to the terminals of the semiconductor device placed on the placing table; and a pressure part moving the heads toward the terminals of the semiconductor device by pressing the upper side contactors so as to elastically deform the upper side contactors.
Additionally, there is provided according to another aspect of the present invention, a contact method that obtains electrical contact with terminals of a semiconductor device, comprising the steps of: placing the semiconductor device on a placing table from above the placing table through an opening of a pressure part, and at the same time, making the terminals of the semiconductor device contact lower side contactors arranged around the placing table; lowering the pressure part so as to press upper side contactors, elastically deforming the upper side contactors, and moving heads of the upper side contactors toward the terminals of the semiconductor device; and making the heads of the upper side contactors contact the terminals of the semiconductor device on a side opposite to the lower side contactors and giving contact pressure to the terminals of the semiconductor device by putting the terminals between the lower side contactors and the upper side contactors.
According to the present invention, it is possible to achieve two point contact merely by pressing the upper side contactors by the pressure part and elastically deforming the upper side contactors so as to put the terminals of the semiconductor device between the upper side contactors and the lower side contactors. Thus, a motion of contact is only pressing the pressure part so as to lower the pressure part. Therefore, it is possible to achieve accurate and positive two-point contact by the same operation as that of a conventional one-point-contact type socket.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the following drawings.